Pulmonary complications of therapy for RA or other benign conditions are often difficult to diagnose and treat. Clinical presentation of lung disease that is due to noncytotoxic drugs may vary from a mild, nonspecific cough to fulminant respiratory failure. The differential diagnosis of pulmonary disease should include drug toxicity, progression of the primary illness, and opportunistic infection. An objective assessment of the patient's baseline pulmonary status, as well as his treatment history, is crucial to differentiate drug-induced pathology from the primary process. Diagnostic work-up should include chest radiograph, repeat pulmonary function testing, and high-resolution CT of the chest. Bronchoscopy for tissue pathology or specific BAL cytokine markers also may yield useful information; occasionally, open-lung biopsy is required. If pulmonary disease that results from noncytotoxic drug therapy is suspected, the drug should be discontinued until the disease process is understood clearly.